Signal network plasticity allows cellular responses to vary in behavior according to varying environmental conditions. Features that contribute to signal network plasticity include: 1. Adaptation or desensitization to persistent stimuli (feedback regulation). 2. Maintenance of pathway specificity while sharing key signaling components. 3. Robust activity in the presence of both environmental and intrinsic fluctuations. 4. Dynamical modulation of pathway activity to encode and transmit information about the cell's surroundings. 5. Dynamical reorganization of sub cellular location and activity of signaling components. 6. Buffering against or robustness to perturbations in pathway components (e. g., deletion, over expression or mutation of signaling components). We believe it is the plasticity of signaling networks that has greatly impaired the ability of single target small molecule therapeutics to be effective in treating human disease (i.e., the frequent absence of single nodes controlling network activation and function). Our proposed studies to define plasticity of the MAPK signaling network allows computational predictions and biochemical, genetic and pharmacological validation of two or more nodes within the network whose combinatorial perturbation will effectively inhibit or re-establish normal dynamics of a disease dysregulated network. The goals of the consortium are to: 1. Complete a comprehensive quantitative proteomic analysis of the MAPK signaling network. 2. Use highly innovative spatio-temporal imaging of the activity of specific GTPases and other proteins controlling MAPK signaling network activity multiplexed with sensors that are able to measure the activity of ERK1/2, p38, JNK, and ERK5 in the same living cell. 3. Use bioinformatics methods to annotate the proteomic datasets and MAPK signaling network analysis for modeling of the MARK network activity and plasticity. Modeling will be used to define MAPK network plasticity and to identify nodes that are critical for plasticity. The models will be experimentally tested in an iterative process with different stimuli, combinations of stimuli and genetic and small molecule perturbation of the MAPK signaling network. 4. Develop small molecule inhibitors of node proteins for use in perturbing network plasticity. The analysis will be tested in cell models where rewiring and dysregulation of the MAPK signaling network is involved in a disease state such as transformation or drug resistance. [unreadable] [unreadable] Relevance to public health: Defining signal network plasticity in this rigorous manner is required for paradigm shifts in our understanding of cell behavior whose dysregulation is at the root of most human diseases that affect people in the western hemisphere. A rigorous definition of signal network plasticity will accelerate the translation of basic discovery to therapeutic intervention of human disease, a stated goal of the NIH mission. [unreadable] [unreadable] [unreadable]